Current lighting devices often employ digital lighting technologies such as light-emitting diodes (LEDs) that generally feature longer operating lives, cheaper operating costs, and wider color ranges than those of legacy lighting devices such as incandescent lamps and fluorescent lamps. However, changing ambient light conditions (e.g., seasonal differences, time of day, subjects in motion) can cause lighting device emissions of a given color to be absorbed by the surrounding environment rather than reflected for perception by the user of the lighting device. Such “light waste” operates counter to the longevity, affordability, and efficiency of lighting devices. Advancements in generation of colored light and adaptation to ambient light hold promise for combating light waste.
Current lighting devices are generally capable of generating light within a diverse color range by combining the emissions of various colored primary light sources. Commonly, devices that combine light to create various colors employ light sources that include red, green, and blue (RGB) colored lights, which are known in the art as primary additive colors or primaries. Additional colors may be created though the combination of these primaries. By combining two primary additive colors in substantially equal quantities, the secondary colors of cyan, magenta, and yellow may be created. Combining all three primary colors may produce white. By varying the luminosity of each color emitted, approximately the full color gamut may be produced.
In general, using fewer lights to produce the full color gamut translates to lower lighting system design and operation costs. For example, in a lighting system that utilizes LEDs, operating every LED at full luminosity to produce a white output color may require using an undesirably large amount of energy and also may produce an excessive amount of heat. Therefore, to emit light of virtually any color within the full color gamut without suffering the shortcomings of the prior art, lighting device implementations in the art are known to add a white light source to supplement the primary color light sources.
U.S. Pat. No. 7,728,846 to Higgins et al. discloses converting an input three-color image data set into an output four-color image data set, where one of the output colors present is white. By including an additional white light source, the white light may provide additional brightness without requiring the primary light sources to operate at full luminosity. However, by adding a new lighting source, the disclosed implementation may not operate with optimal efficiency characteristics based on environmental factors. Furthermore, the disclosed implementation requires the use of light sources defined within the full color gamut to reproduce light in various colors, contributing to inefficient operation.
U.S. Pat. No. 7,324,076 to Lee et al. similarly discloses the use of three or more primary lights in an adaptive lighting solution that receives a user-selected color point, derives tristimulus values for the color point, and controls a plurality of LED drivers for an LED light source to achieve the user-selected color point. However, if the user-selected color point is outside a color selection range of the LED light source, the event is merely flagged as an error and no alternative operation is described. Furthermore, like the Higgins patent, the use of three or more primary light sources to reproduce light in various colors results in operational inefficiency compared to implementations employing fewer than three light sources.
International Pub. No. WO 2006/001221 by Nagai et al. discloses a method for altering the light source color of room illumination in accordance with the season, time of day, and occasion. The illumination source emits light in a light source color created as a result of sufficiently mixing white light from white LEDs and orange light from orange LEDs. However, the light source color is variable without deviating much from a state close to natural light, and without regard for possible absorption of the produced color by the environment surrounding the light source.
A need exists for a light adapter that may accept a source signal defining a selected color, and that may efficiently manipulate less than three color points generated by primary light sources along with a white color point generated by a high efficacy light source to produce a selected color. Additionally, a lighting device with the ability to adapt to a selected color would be able to dynamically increase its efficiency by allowing for reduced light absorption by the lighting device's environment, which is more desirable to both consumers and producers. More specifically, a need exists for a lighting device with the ability to adapt to its environment so that more of its produced light is reflected rather than absorbed, increasing efficiency. Additionally, such a lighting device may need to adapt multiple times to account for changes in its environment.
This background information is provided to reveal information believed to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.